The present invention relates generally to the field of separation processes. More particularly, it relates to a method for separating contaminants from a vapor stream.
The need for suitable methods for effectively removing contaminants from process steam streams prior to discharge to the atmosphere is becoming increasingly important due to the more stringent limitations on the amount of contaminants that may be released to the atmosphere. A number of commercial processes for scrubbing vapor streams with a liquid to remove contaminants have been developed. Typical separation processes and apparatus are shown in U.S. Pat. Nos. 3,803,805 and 3,533,608. However, a simple, reliable separation process for effectively scrubbing contaminants from steam streams is still needed to meet the ecological demands of the market place. Therefore, it is desired to develop an economical and efficient process for the removal of contaminants from steam streams.
The present method provides such a simple, yet efficient method of removing contaminants from process steam streams, and in addition offers a number of advantages over conventional processes. For example, the contaminated scrubbing water removed in the present process (commonly termed "underflow") has a contaminant concentration considerably higher than "underflow" concentrations typically observed in other scrubbing processes such as Venturi scrubbers and spray towers. This increased concentration reduces the amount of scrubbing liquid required for efficient contaminant removal. More importantly, the negligible dilution of the underflow allows the contaminated scrubbing water to be recycled to a suitable evaporator. Conventionally, the typical underflow is uneconomical to evaporate and is discharged to the environment.
Another significant advantage of the present process is the reduction of large differences in the pressure of the steam entering and leaving the scrubber. In situations where the steam scrubbed by the present method is to be further used in subsequent processes, pressure drops across the scrubber are not only undesirable, but are also uneconomical.
Still another advantage of the present process is the elimination of contaminant plugging problems generally encountered in demisters, sieve plates, packed column and other similar method of contaminant removal.
These advantages and other benefits achieved by the present method will become clear by the following detailed description of the process.